I reached out to Fassler, who regularly interviews writers for The Atlantic's "By Heart" series, to ask if he could share lessons about creativity from Light the Dark that would be useful to innovators. This is his reply:

We tend to treat creative artists as if they're, well, different than the rest of us, but writing is like every other job for most authors. There's drudgery, setbacks, and grueling deadlines, joy and disappointment, occasional breakthroughs. Most days are the same: It's about trying to solve complex challenges as efficiently as possible, with as much creativity and flair as one can muster, without losing heart.

Here are the most useful, universal lessons I've learned, applicable in any difficult endeavor.

1. Trust incremental progress.

Not all writers write daily, but most feel the most important thing is showing up. The only way to ensure zero progress is by never sitting down at the desk in the first place. It's about clocking in every day and trusting that even small, effortful steps forward are worthwhile.

"There won't be joy every day, every sentence, in everything you do. It doesn't work like that," Neil Gaiman explains in his contribution to Light the Dark. "You're going to write on the good days, and you're going to write on the bad. You're going to write on the days you've got a migraine and the day your wife left you. You're going to write on the days when you sit down light and happy of heart." But no individual session makes or breaks the book--and the finished product, he says, is just a "wall you built by taking the word and putting it, and taking another one, and taking another one."

Success, in other words, rarely comes in huge flourishes. Instead, it rewards patience over the long haul. The battle is fought in countless skirmishes, one day at a time.

2. Learn to adapt.

Few authors write exactly the book they set out to write. That's because what seems appealing in the abstract usually ends up being much more complicated in practice.

For writers, that can mean being ruthless about abandoning cherished material--a favorite character, a winning passage, a formal innovation, sometimes an entire manuscript--when it turns out not to work. Amy Tan, author of The Joy Luck Club, told me she discards a full 95 percent of what she writes. Andre Dubus III, author of House of Sand and Fog, put it this way: "I don't care if I spent a year writing pages 1 through 96. If I feel some real energy on page 93, and I think that should be page 1? Those first 92 pages are gone."

It's tough to admit when a strategy isn't working. But adaptation isn't a sign of failure--it's a way of generating future opportunity. The Man Booker-winning novelist George Saunders told me he swears by a famous Einstein quote: "No worthy problem is ever solved in the plane of its original conception." So don't be too reliant on the route you'd hoped to take. And when you're forced into unfamiliar territory, trust that your values, instincts, and hard skills will eventually bring you to the right place.

3. Keep your eyes open.

Transformative ideas only come along so often, and you never know when one will find you--in a mediocre college seminar, after a bad breakup, drifting lazily through a used bookstore. Yet the writers I talk to have one thing in common: They're on the lookout.

"You could be staying in some guesthouse anywhere in the world, and there are three books there, and one of them changes your life," says the writer and critic Eileen Myles. The idea for your next bold venture might just be sitting there, on an everyday shelf. You just need to remember to take the time to look.